Say about it what you will, but in an election year, you can’t accuse Kevin Costner’s political satire Swing Vote of failing to keep up with current events. With an eye on the box office coffers and a finger on the nation’s nervous pulse, this romp with a conscience, directed by Joshua Michael Stern, who co-wrote the edgy screenplay (with Jason Richman), features the new scruffy, self-deprecating and slightly graying Mr. Costner dispensing oodles of paunchy charm as the unlikeliest American voter who ever turned cynical indifference into civic pride and a nation upside down. He is really engaging as a polecat from Texico, N.M., named Ernest “Bud” Johnson, a divorced single father who is such a lazy loser he can’t even hold down a no-brainer job at the local egg-packing plant. Bud is quite a challenge to his patriotic daughter Molly (newcomer Madeline Carroll, a genuine challenger to Little Miss Sunshine’s Abigail Breslin), who picks up his empty beer bottles and spends an inordinate amount of time trying to get him out of bed. It’s Election Day, and Bud refuses to vote, fretting that it might mean jury duty. Precocious Molly sneaks into the polling place just before it closes and casts her indolent dad’s vote for him, forgetting to pull the lever. The result is that with only five electoral votes, New Mexico turns out to be the swing state and Bud’s irregular ballot is the deciding vote that will throw the election. What follows is the equivalent of a sudden landslide for Ralph Nader.

Before he can recast his vote properly, every political power in Washington descends on Texico to influence the one man who will choose the next president, opening a floodgate for an all-star cast of scenery-chewing comics (Nathan Lane, Stanley Tucci, George Lopez, Willie Nelson) and a circus of gibberish-dispensing media pundits (Chris Matthews, Aaron Brown, Tucker Carlson, Tony Blankley, James Carville, Larry King, Bill Maher, Campbell Brown—even Mary Hart, for chrissake!) to invade Bud’s mobile trailer, competing for more interviews than the press corps trailing Obama in Iraq. Shrieks the manager of the local TV station when they arrive by bus, helicopter, and even Air Force One to put Texico on the national news: “This is bigger than O. J.!”

In the 10 days the Registrar of Voters gives Bud to recast his ballot, every fruitcake in Washington tries to influence his decision, and everything from Planned Parenthood to Outback Steakhouse wants a piece of the action. Both the Republican incumbent (Kelsey Grammer) and his Democratic left-wing rival (Dennis Hopper) appeal to Bud on every issue from immigration to global warming, doing and saying whatever it takes to get elected, and Bud becomes the composite market demographic that all the campaign strategists of Obama, Clinton and McCain have been groveling for all year. Mr. Costner is hilarious as he struts forth from his perch at the local bowling alley to awkwardly declare his views on everything from the environment to gay marriage. Funny, animated, appealing in an aw-shucks sort of way, the star milks maximum impact from a unique body language that is refreshingly knock-kneed and bow-legged at the same time.

It all leads up to a televised presidential debate in which Bud gets to ask questions of both candidates, and you get the horrible feeling you’ve seen and heard it all before on CNN. This is numbingly preposterous, of course, until you realize every joke is based on the crazy-quilt Cuisinart we’ve made of the U.S. Constitution, and the humor comes painfully close to election-year reality.Finally, perennial talking head Arianna Huffington faces the camera and says loftily to the brain-dead American public, “Something tells me Franklin and Jefferson are looking down and smiling.” Moaning in pain and disbelief is more like it. Does this election hurt? Only when we laugh.